Currently not working with Gitlab CE 8.3!
Run the container using the following command and adapt the environment variables and port as necessary.
docker run -d -e TOKEN=YOURTOKEN -e GITLAB_HOST=https://gitlab.example.org -p 8080:8080 herzog31/gitlab-coverage-badge
If your project in Gitlab is named name/project, then you find its coverage badge at:
http://your.docker.host/name/project.svg
Currently, only output as SVG is supported.